According to the official rhetoric, we are now in the 25th year of the AIDS pandemic. The anniversary refers to the first diagnosis of the disease in San Francisco in 1981. Yet this "anniversary" reveals something deep and tragic about our approach to the disease. In fact, the disease is roughly 75 years old, as it originated in Africa sometime around 1930. By 1981 there were perhaps 1 million Africans already infected with the HIV virus, and tens of thousands or more were dying each year. We therefore date the disease to 1981 mainly because the lives, and deaths, of impoverished Africans have been so readily overlooked for so long. The discovery of AIDS came only when the disease claimed lives outside of its continent of origin.
The scientific dating of the emergence of AIDS is based on a genetic "clock" of the HIV virus. AIDS as a human disease is new and came into existence when a chimpanzee virus (Simian Immunodeficiency Virus, or SIV) spread from chimpanzees to humans somewhere in West Africa around 1930. The best and most recent guess for the actual site of this "zoonosis," the transfer of the pathogen from animals to humans, is Cameroon. Of course the event itself is lost to history. It may have resulted from a hunter butchering or eating the bush meat of a chimpanzee infected with SIV, followed by a mutation of SIV to HIV. The genetic changes from SIV to HIV provide the biological clock that scientists use to determine the most likely date and site of the new disease's emergence.
Between the 1930s, or thereabouts, and 1981, the disease mainly spread throughout Africa. By looking back at stored blood samples in Africa from the 1960s and 1970s, some early HIV/AIDS cases have been identified decades after the fact. By 1981, when the disease was finally diagnosed in the U.S., perhaps one million Africans were already infected. This number can be estimated by running the epidemic "backwards," to account for the fact that by the early 1990s there were already many millions of Africans infected with HIV.
Of course by the time that the disease was first recognized in 1981, the HIV/AIDS epidemic had already spread silently and massively to all parts of the world, including the U.S. By neglecting the deaths of the poorest of the poor in Africa for so many years, the richest of the rich in other places of the world were thereby also left vulnerable. The prophetic wisdom that when lives are neglected anywhere, lives are at risk everywhere proved again to be dramatically true. And the same lessons apply to new zoonotic diseases of today, such as avian flu, which once again is spreading across national boundaries.